CONICET | Buscador de Institutos y Recursos Humanos

The polyprotein allergens/antigens of nematodes (NPAs) are small, helix-rich proteins, and have no known structural counterparts in other phyla, including the animals and plants in which parasitic nematodes cause so much harm. The term polyprotein refers to the production of NPAs as large precursors comprising tandemly repeated units that are cleaved posttranslationally into multiple ~15 kDa protein units which may have similar or different functions. The biochemical activity of the NPA of A. suum was first described as a binding protein for small lipids such as fatty acids and retinoids. Recently, the structure of a single unit of the polyprotein array has been solved in the presence of saturating concentration of oleic acid describing two binding sites. In the present project we are working with ABA-1A in the absence of the ligand (apo form) and its atomic structure is under analysis employing NMR spectroscopy, for which high quality data have already been obtained and full structure calculation is in progress. Another interesting issue is that the structure and ligand-binding characteristics of these proteins have been demonstrated for single units of the polyprotein, but not for two units in tandem from the same polyprotein array. To get further insight into possible interactions between units when still being part of the polyprotein array, we designed a tandem repeat of the unit ABA-1A of the parasitic nematode Ascaris suum. The construction is underway employing PCR. After expressing the recombinant tandem we aim at analyzing its structure and lipid binding characteristics in comparison with the single unit?s. Additionally, we are exploring for NPAs in the parasitic nematode Haemonchus contortus. Up to date, we have the complete RNAm and protein sequence using public databases and gene prediction softwares.